hello. I am 17 years old, about 6' tall and weigh about 135lbs. I have had no previous medical conditions involving my respiratory or cardiovascular health. About 5 days ago (January 2nd) I woke up with pains in my left pectoral, directly below my left shoulder blade, and in the left side of my neck (muscle). When I first woke up I just thought I had pulled some muscles from the day before or slept on my left side funny so I rubbed A5-35 on the effected areas which resulted in some relief but I still had the same pains just to a lesser extent. I then was searching the web as the pain got worse throughout the day and it convinced me that my body was getting ready to have a heart attack or another cardiovascular issue so I went to the hospital emergency room around 5-6:00pm that day. They took x rays and blood tests and also hooked me up to a EKG and said they saw nothing wrong. My family doctor called me one day later to tell me he was almost sure he sees a small pneumothorax in my left lung and I needed more x rays and the first were unclear. He also said it was very small, did not cause my lung to collapse, and should be healed on its own naturally as he could not hear anything abnormal after listening to my breathing through a stethoscope. I do not have much or any lung pain but both lungs do feel off/weird (kind of a lightly bruised feeling) and my pectorals feel like I just went through a hard chest workout. I have taken it easy on my body the last few days by not exercising or lifting anything heavy. Since the first incident, every time I lay or put any pressure on my back (i.e. Sitting with my back on a chair, leaning on it, etc) my chest makes sort of a very light popping noise as your knuckles so when you crack them. This only happens when I breathe and does not when I hold my breathe and ONLY happens when there is pressure on my back. I can feel the cracking slightly, it is not painful what so ever however it does scare me. I got more x rays on January 4th, as requested by the doctor, and he did not wish to have a follow up appointment after reviewing the results (I knew he reviewed the results because I called his office asking if I needed to come in). Any ideas?? I'm kind of scared and don't what that this is, what is happening, and if it is normal or not. No body I ask states they've heard of it before. Any help is useful. Thanks